Integrated carbon dioxide capture

ABSTRACT

A method/system for sequestering carbon dioxide from cement and lime production facilities wherein carbon dioxide from flue gases originating from cement or lime production facilities is recovered and transported to a building materials production facility where it is sequestered.

CROSS-REFERENCE

This application is a continuation of PCT International ApplicationSerial No. PCT/CA2015/050195, filed Mar. 16, 2015, which claims thebenefit of U.S. Provisional Application No. 61/976,360, filed Apr. 7,2014, which applications are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Worldwide production of cement resulted in 3.6 billion tons of cementproduced in 2012 and 1.7 billion tons of carbon dioxide released duringthe production of that cement. There is a need to efficiently sequestersome or all of the carbon dioxide released in the production of cement.Concrete consumption was conservatively estimated to exceed 15 billiontons in 2012, although no precise records are available. The totalamount of carbon dioxide emitted to produce one ton of cement will varydepending on the type of process, raw materials, and fuel combusted, butis roughly about 600-800 kg of CO₂/ton of cement produced.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

DETAILED DESCRIPTION OF THE INVENTION

Cement and lime production releases CO₂ gas by two mechanisms; thecalcination of limestone in the raw materials and the combustion offuels used in the cement and lime manufacturing processes. For thisreason, the flue gases from cement and lime production are some of therichest sources of flue gas carbon dioxide. At present this carbondioxide is generally vented to the atmosphere.

Because of these two sources, the carbon dioxide content of flue gasfrom cement and lime manufacture may be 14-33% by volume, compared to 4%for a natural gas fired combined cycle power plant and 9-15% for a coalfired power plant. Higher concentrations of CO₂ in the flue gasgenerally require lower costs for capture of the CO₂.

The present invention provides integrated methods and compositions forintegrating carbon dioxide from cement and lime manufacture and theirrespective flue gases back into manufacturing processes, such as thecement or concrete manufacturing process; for example, incorporating thecarbon dioxide into building products and other products thatincorporate a mineral binder, e.g., a cement binder such as Portlandcement, that provides minerals, e.g. calcium, magnesium, sodium, and/orpotassium minerals such as CaO, MgO, Na₂O, and/or K₂O that react withthe carbon dioxide to form carbonate (CO₂) bonded products at thebuilding product end of the method or system. Although any binder thatprovides sufficient minerals and other components to be converted tomineral carbonates upon application of carbon dioxide may be used, forconvenience the methods and systems will be described in terms ofcements, such as Portland cement. Alternative or additional uses of thecarbon dioxide include cooling concrete mixes, e.g., with liquid carbondioxide, and/or treating process water, for example, to adjust pH to anacceptable level.

In certain embodiments, the invention provides an integrated approach,in which carbon dioxide released from the production of cement at acement manufacturing facility is used in the process itself, forexample, converted to a stable carbonate form, such as a calcium ormagnesium carbonate or other carbonate form, in a building material,thus lowering overall carbon dioxide emissions and providing for greaterefficiency in the collection, transport, and use of carbon dioxide inthe building materials. It is possible with the integrated approach ofthe invention, that the same carbon dioxide that was released duringproduction of a cement, such as a Portland cement, and used in abuilding product will be recaptured in the building product duringcarbonation. However, the carbon dioxide from the cement manufacturingprocess may also be used in other types of building products that don'tcontain the cement produced at the specific facility. In addition oralternatively, the carbon dioxide may be used in other aspects of themanufacturing process, such as in cooling concrete and/or treatment ofprocess water.

Cement and lime production is universal and fairly evenly distributedaround North America and the world. Cement production stays fairly closeto concrete usage due to the relatively high cost of shipping. Thus, inthe integrated approach of the invention, transportation costs for theCO₂ are minimized, as it is produced at the cement manufacturingfacility and may be used at a concrete production facility within ashort distance.

The cement and lime manufacturing facilities may utilize any suitablemanufacturing process so long as a flue gas is produced at one or morepoints from which carbon dioxide may be concentrated and separated. Incertain embodiments the cement and lime manufacturing processes mayinclude rotary kilns. In certain embodiments, the cement and limemanufacturing processes may include preheaters. In certain embodimentsthe cement manufacturing process may include a precalcination vessel(Precalciner).

Carbon dioxide may be concentrated and/or extracted from the cement andlime manufacturing processes by any suitable method, such aspre-combustion, oxy-combustion, and post-combustion methods. Anysuitable method that generates carbon dioxide of sufficientconcentration and purity can be used for the production of buildingmaterials.

In certain embodiments the CO₂ gas stream may be concentrated beforeextraction by such means as oxy-combustion and/or indirect calcination.In certain embodiments the CO₂ gas stream may be concentrated due topre-combustion technologies such as the use of metal oxides, etc. Incertain embodiments, the carbon dioxide is separated post-combustion. Incertain embodiments, the carbon dioxide is separated by use of solid orliquid sorbents, for example, carbonate looping or amine sorbents. Incertain embodiments, the carbon dioxide is separated by use ofmembranes. In certain embodiments, the carbon dioxide is separated byuse of cryogenic technology. In certain embodiments, the carbon dioxideis separated by carbonate looping. Any such means of concentrating andextracting a CO₂ gas stream from the cement and lime manufacturingprocesses may be used.

In certain embodiments the CO₂ may already be available in asufficiently concentrated form. These embodiments include the potentialuse of pre-combustion technologies, oxy-combustion, indirectcalcination, etc. In addition, various parts of the cement and limemanufacturing processes produce higher concentrations of carbon dioxidethat may be more easily extractable. In particular, in certainembodiments of the invention carbon dioxide is separated from the kilnor preheater flue gas, such as gas from the kiln or preheater exitbefore or after the kiln/preheater exhaust fan. In these embodiments,the gas may be cleaned, e.g., in a fabric filter, and or cooled to anadequate temperature before further processing. If necessary, additionalimpurities may be removed at this point. A preferred embodiment utilizesthe flue gas with the highest concentration of CO₂ and the lowest costfor additional treatment, such as the preheater exhaust gas at thedischarge of the exhaust fan.

The concentration and the purity of the carbon dioxide need be nogreater than that required by the process in which the carbon dioxide isintroduced into the building materials, and/or used in other processesin cement or concrete manufacturing. In general, it is not necessary toachieve food grade carbon dioxide quality. In certain embodiments, acarbon dioxide content of greater than 60%, such as greater than 80%,for example, greater than 90%, with a level of other elements, such asSOx, low enough so as not to interfere with the reuse of the CO₂, forexample, its introduction into a building product, or use in treatingprocess water, is sufficient. For example, when used in the manufactureof building products, any suitable carbon dioxide content and purity maybe used, as long as the quality of the building product is sufficientfor its intended purpose, e.g., use of Portland cement in makingconcrete or mortar.

In certain embodiments, only a portion of the flue gas from themanufacturing processes is used in a treatment process to separateuseable carbon dioxide from the flue gas. The portion of flue gastreated may be less than 90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6,5, 4, 3, or 2% of the total flue gas produced by the cement or limemanufacturing process. In certain embodiments, the portion of the fluegas treated is less than 10%, for example, less than 7%, such as lessthan 6%. In certain embodiments, the portion of the flue gas treated toseparate carbon dioxide is 1-90%, or 1-70%, or 1-50%, or 1-30%, or1-20%, or 1-10%. In certain embodiments, the portion of the flue gastreated is 1-10%. In certain embodiments, the portion of the flue gastreated is 1-8%. In certain embodiments, the portion of the flue gastreated is 1-6%. In certain embodiments, the portion of the flue gastreated is 2-8%. In certain embodiments, the portion of the flue gastreated is 2-6%.

In some cases, impurities which normally would be removed before theflue gas is vented to the atmosphere may remain present in the CO₂separated from the flue gas; if these are not harmful to the process ofmaking and/or using the building product, e.g., cement/concrete, intowhich the CO₂ will be introduced. Impurities can include NOx, SOx, HCl,dust, metals, CO and/or volatile organic compounds (VOCs). It cantherefore be advantageous to leave them in the CO₂ separated from theflue gas; for example, if the carbon dioxide is used in producingbuilding materials, in many cases these constituents will themselvesbecome sequestered in the building product, e.g., cement/concrete, intowhich the CO₂ is introduced, e.g., by chemical reaction to producerelatively inert substances and/or by physical entrapment. In eithercase, it may be possible to avoid the expense of cleaning the flue gaswhich would otherwise be required, or use a minimal cleaning.

The efficiency of the process is increased over use of purchased carbondioxide because of reduced transportation costs, and in addition, energycosts in the production of the carbon dioxide may be lower than intypical carbon dioxide extraction processes because waste heat from thecement or lime production process can be used in the extraction,concentration, or other treatment of the flue gas. Thus, in certainembodiments of the invention, waste heat from the cement and limemanufacturing processes may be used in various processes involved in theconcentration, extraction, and/or other treatment of the flue gases.Heat sources include; the waste heat from the preheater exit gasesand/or the cooler vent air, radiant heat from the rotary kilns, etc. Incertain embodiments, waste heat from a preheater is used in theconcentration and/or extraction of carbon dioxide from flue gas. Incertain embodiments, waste heat from a cooler is used in theconcentration and/or extraction of carbon dioxide from flue gas. Incertain embodiments, waste heat from both a preheater and a cooler isused in the concentration and/or extraction of carbon dioxide from fluegas.

Depending on the separation technology and the transport requirements,the carbon dioxide produced may be gas, liquid, solid, or supercritical.In certain embodiments, the carbon dioxide is primarily or entirelygaseous. In certain embodiments, the carbon dioxide is primarily orentirely liquid. Liquid carbon dioxide offers the advantage of easy andefficient transport, and in some cases the carbon dioxide used in theproduction of building materials is required to be in liquid form. Inaddition, where cooling of concrete or concrete materials is desired,liquid carbon dioxide is a useful coolant source.

Various processes have been proposed for the capture of carbon dioxidein building products, for example, capturing carbon dioxide in productsthat comprise a mineral binder, such as a cement, e.g., Portland cement,that contains calcium in an environment such that carbon dioxide willreact with the calcium to form calcium carbonate. The carbon dioxideused may be from any source.

Any suitable separation technology may be used; many such technologiesare known in the art and any technology that produces a product ofsufficient carbon dioxide concentration and, if appropriate,sufficiently low impurities, to be used in the desired processes incement and/or concrete production, for example, the production of stablecarbonates, and/or cooling concrete or concrete components, and/ortreating process water, may be used.

An exemplary technology is cryogenic separation; this is exemplary onlyand not limiting to the type of separation technology used. In one suchcryogenic separation process the flue gas stream is dried and cooled,then modestly compressed and cooled to slightly above the frost point ofCO₂. The gas is then expanded, further cooling the stream andprecipitating solid CO₂, which is separated from the remaining flue gas.The pure solid CO₂ stream is the further pressurized to a liquid state.The cooled CO₂ and N₂ can be used in a heat exchanger to cool incomingflue gas. The final result is the CO₂ in liquid phase and a gaseousstream comprised primarily of nitrogen. The liquid CO₂ may be generatedand stored at the producing site, and transported as needed to a sitewhere building products are produced, e.g., concrete. Transport may beby any suitable method, such as by road or rail, or pipeline, or acombination thereof. Pipelines can be used for both gaseous and liquidcarbon dioxide. The carbon dioxide may be transported as solid, gas,liquid, or any suitable combination thereof. The choice of transportform can depend on the intended final use.

The CO₂, e.g., liquid CO₂, may be transported to the site of use, e.g.,a building products production facility. In general, such a buildingproducts facility will use the cement and/or lime produced in the cementor lime manufacturing processes from which the carbon dioxide wasobtained; such building material facilities are often close to thecement and/or lime manufacturing facilities, such that the carbondioxide is transported less than 500, 400, 300, 200, 100, or 50 miles.Thus, in certain embodiments, carbon dioxide is concentrated and/orextracted from a flue gas at a first facility, e.g., a cement and/orlime production facility and transported no more than 500, 400, 300,200, 100, or 50 miles, to a second facility that is a concreteproduction facility, and used in one or more processes in the secondfacility, such as in carbonation of concrete, treatment of processwater, and/or cooling of concrete or a concrete component. Exemplaryfacilities are ready mix concrete batching facilities and precastconcrete facilities. In certain embodiments, the carbon dioxide is usedin the process of producing a building product, such as concrete orprecast concrete products. The CO₂ may be used at any suitable stage ofthe process of producing the building product, e.g., during mixing ofthe concrete, where it may be introduced into the mixing concrete, suchas in a ready mix operation or a precast operation; or post-mixing butupstream from a mold in a precast facility, e.g., in a hopper, orfeedbox, or introduced into a stream of concrete moving from hopper tofeedbox or feedbox to mold; or at the mold itself, or any combinationthereof. In certain embodiments liquid CO₂ derived from flue gas at acement or lime manufacturing facility is introduced into mixingconcrete, e.g., concrete containing at least a portion of the cementproduced at the cement manufacturing facility. This is, in a sense, acalcium carbonate cycle, with carbon dioxide released from calciumcarbonate (limestone) at the cement or lime manufacturing facility andreconverted to calcium carbonate in the concrete (or any other buildingmaterial comprising the necessary minerals, e.g., calcium, to react withthe carbon dioxide). Details of use of carbon dioxide in concrete andconcrete materials may be found in U.S. patent application Ser. No.13/660,447; PCT/CA 2014050611, filed Jun. 25, 2014; U.S. patentapplication Ser. No. 14/249,308, filed Apr. 9, 2014; and U.S.Provisional Patent Application 61/992,089, filed May 12, 2014; all ofwhich are incorporated by reference herein in their entireties.

Carbon dioxide obtained from cement and/or lime production mayadditionally, or alternatively, be used in other aspects of the processof production of building materials. For example, in concreteproduction, process water is produced in various stages of theproduction and packaging process, such as truck cleanout and otherprocesses, where the process water has a high pH that must be reducedbefore the water can be discharged. Current treatment methods includethe use of HCl, but the process is difficult to control and has safetyissues involved with handling a concentrated acid. An alternative methodutilizes carbon dioxide addition to the process water. The carbondioxide forms carbonic acid, a weak acid, that is converted tobicarbonate and ultimately carbobnate (e.g., calcium carbonate). As thepH is lowered by these reactions, it eventually reaches 7 or 8, and theprecipitated calcium carbonate dissolves, creating calcium bicarbonate.Because of the pKas of the various reactions, the system is buffered andit is easier to achieve the desired pH for discharge. Thus, certainembodiments provide treatment of process water from a manufacturingprocess that produces high-pH process water, such as concretemanufacture, with carbon dioxide produced in lime and/or cementmanufacture to lower the pH of the process water. The carbon dioxidefrom the lime and/or cement manufacture may constitute any suitableproportion of the total carbon dioxide used in the water treatmentprocess, such as at least 10, 20, 30, 40, 50, 60, 70, 80, 90, 95, or 99%of the carbon dioxide used in the water treatment process, and/or notmore than 20, 30, 40, 50, 60, 70, 80, 90, 95, 99, or 100% of the carbondioxide used in the water treatment process.

An additional or alternative use of carbon dioxide from lime or cementproduction is in cooling components of concrete, or concrete itself.This can be especially important when concrete is manufactured in warmtemperatures, as concrete can be too hot when produced conventionally,so producers cool the raw materials and/or mixed concrete using ice orliquefied gases. Chilled carbon dioxide, e.g., as a gas, solid, liquid,or combination thereof, may be used in one or more aspects of theseprocesses. For example, certain processes for chilling aggregate may useliquid nitrogen or liquid carbon dioxide, sprayed into a cylindercontaining aggregate, to cool the aggregate before its use in themanufacture of concrete. See, e.g., U.S. Pat. No. 5,220,732. In otherprocesses, a chilled fluid, such as liquid nitrogen, argon, oxygen,chilled water, or carbon dioxide is applied directly to a mixingconcrete mix to cool the temperature of the mix; it will be appreciatedthat if carbon dioxide is the cooling fluid, carbonation of the mix islikely to occur. In addition, it is possible to apply both gaseous andsolid carbon dioxide, produced from liquid carbon dioxide, to a concretemix or a component of a concrete mix, to achieve both carbonation andcooling. See, e.g., U.S. Pat. No. 8,235,576; U.S. Patent ApplicationPublication No. 2014 0216303; and PCT Patent Application No. PCT/CA2014050611, filed Jun. 25, 2014. Thus, certain embodiments providetreatment of a concrete component, such as aggregates, or concrete, withcarbon dioxide produced in lime and/or cement manufacture to lower thetemperature of the component. The carbon dioxide from the lime and/orcement manufacture may constitute any suitable proportion of the totalcarbon dioxide used in the concrete or concrete component treatmentprocess, such as at least 10, 20, 30, 40, 50, 60, 70, 80, 90, 95, or 99%of the carbon dioxide used in the concrete or concrete componenttreatment process, and/or not more than 20, 30, 40, 50, 60, 70, 80, 90,95, 99, or 100% of the carbon dioxide used in the concrete or concretecomponent treatment process. In certain embodiments, the process is aprocess of cooling aggregate to be used in a concrete production processto a desired temperature. In certain embodiments, the process is aprocess of cooling a concrete mix.

The carbon dioxide may be used in cement or concrete productionprocesses, e.g., the production of building materials at low pressures,treatment of process water, and/or cooling of concrete or concretecomponents, e.g., at a pressure of 0-25 psi, or 0-50 psi, or 0-100 psi;alternatively, the carbon dioxide may be used at high pressure, e.g., ata pressure of greater than 50, 100, 150, 200, 300, 400, or 500 psi,depending on the desired use.

In one embodiment, the invention provides a method of sequesteringcarbon dioxide from a cement manufacturing facility comprising i)treating flue gas comprising carbon dioxide from the discharge of apreheater exhaust fan at the cement kiln to render the carbon dioxidetransportable, e.g., concentrating the carbon dioxide; ii) transportingthe carbon dioxide to a building materials production facility; and iii)performing at least one operation of treating one or more buildingmaterials with the carbon dioxide in such a manner as to permanentlysequester the carbon dioxide; treating a process water produced in thebuilding materials facility with the carbon dioxide to lower a pH of theprocess water, or treating concrete or a concrete component at thebuilding materials production facility to cool the concrete orcomponent. In certain embodiments, at least two of the operations areperformed with the carbon dioxide at the building materials productionfacility. In certain embodiments, all three of the operations areperformed with the carbon dioxide at the building materials productionfacility. In general less than the entire exhaust flue gas of thepreheater is treated to render the carbon dioxide transportable, forexample, less than 50%, or less than 40%, or less than 30%, or less than20%, or less than 10% of the total flue gas produced by the preheater.The transportable carbon dioxide may be liquid carbon dioxide, solidcarbon dioxide, or gaseous carbon dioxide, or any combination thereof,and transported by road, rail, or pipeline (liquid and gaseous carbondioxide) to the building materials production facility. The buildingmaterials production facility can be a ready mix facility or a precastfacility, and in some cases the cement used at the facility includes thecement produced at the cement manufacturing facility; thus, the entireloop of separation of carbon dioxide and its use in a building materialmay occur within a radius of less than 500, 400, 200, 100, 80, 60, 50,or 40 miles. If the carbon dioxide is mostly or entirely liquid, it maybe used in the production of the building materials in liquid form or,in some cases, in liquid form that is converted upon release to mixingbuilding material to solid and gaseous forms. In some cases, the carbondioxide may alternatively, or additionally, be introduced into abuilding material, e.g., concrete, under pressure, such as when theconcrete is pumped through a conduit at a building site. Admixtures mayalso be introduced into the concrete treated with the carbon dioxidefrom the cement kiln to modulate, e.g., flowability and/or earlystrength development.

In one embodiment, the invention provides a method of sequesteringcarbon dioxide from a cement kiln comprising i) treating flue gascomprising carbon dioxide from the cement kiln to render the carbondioxide transportable in liquid form; ii) transporting the carbondioxide to a building materials production facility; and iii) treatingone or more building materials with the liquid carbon dioxide in such amanner as to permanently sequester the carbon dioxide.

In one embodiment, the invention provides a method of sequesteringcarbon dioxide from a cement kiln comprising i) treating flue gascomprising carbon dioxide from the cement kiln to render the carbondioxide transportable; ii) transporting the carbon dioxide to a concreteproduction facility; and iii) treating a wet concrete mix at theconcrete production facility with the carbon dioxide to sequester thecarbon dioxide in a concrete product.

In one embodiment, the invention provides a method of sequesteringcarbon dioxide from a cement kiln comprising i) treating flue gascomprising carbon dioxide from the cement kiln to render the carbondioxide transportable; ii) transporting the carbon dioxide to a precastconcrete production facility; and iii) treating a precast objectcomprising a cement binder with the carbon dioxide, wherein thetreatment with carbon dioxide occurs upstream of a curing operation.

In one embodiment, the invention provides a method of sequesteringcarbon dioxide from a cement kiln comprising i) treating flue gascomprising carbon dioxide from the cement kiln to render the carbondioxide transportable; ii) transporting the carbon dioxide to a buildingmaterials production facility; and iii) treating one or more buildingmaterials with the carbon dioxide to permanently sequester the carbondioxide wherein the carbon dioxide is contacted with the buildingmaterial at a pressure of 0-25 psi. In certain embodiments, the carbondioxide is contacted with the building material at high pressure, forexample, greater than 100, or greater than 200, or greater than 300 psi.

In one embodiment, the invention provides a system for integratingcarbon dioxide supply and utilization comprising i) a cement kilncomprising a flue gas exit; ii) an apparatus operably connected to theflue gas exit configured to convert carbon dioxide in the flue gas intotransportable form; iii) a transport apparatus for transporting thecarbon dioxide; iv) a building materials facility configured to use thecarbon dioxide in one or more building materials in such a manner as topermanently sequester the carbon dioxide; and v) a transport pathconnecting the cement kiln and the building materials facility, whereinthe transport path is of sufficient strength to allow the transportapparatus to move over it from the cement kiln to the building materialsproduction facility, and wherein the transport path is at least 5 kmlong. The transport path may be, e.g., a pipeline, a road or a railroad.

In any of these embodiments, the carbon dioxide from the cement kiln mayadditionally or alternatively be used in treating a process waterproduced in the building materials facility with the carbon dioxide tolower a pH of the process water, or treating concrete or a concretecomponent at the building materials production facility to cool theconcrete or component. In certain embodiments, at least two of theoperations are performed with the carbon dioxide at the buildingmaterials production facility. In certain embodiments, all three of theoperations are performed with the carbon dioxide at the buildingmaterials production facility

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein may be employed in practicing the invention. It is intended thatthe following claims define the scope of the invention and that methodsand structures within the scope of these claims and their equivalents becovered thereby.

What is claimed is:
 1. A method of sequestering carbon dioxide from cement and lime production facilities comprising i) treating flue gas produced at the cement and/or lime production facility to render the carbon dioxide transportable, wherein the amount of flue gas treated is 1-8% of the total flue gas produced at the cement and/or lime production facility; ii) transporting the carbon dioxide to a building materials production facility; and iii) performing at least one operation of (a) treating one or more building materials with the carbon dioxide in such a manner as to permanently sequester the carbon dioxide in the building material; (b) treating a process water produced in the building materials facility with the carbon dioxide to lower a pH of the process water, or (c) treating concrete or a concrete component at the building materials production facility to cool the concrete or component.
 2. The method of claim 1 further comprising concentrating the carbon dioxide.
 3. The method of claim 1 wherein at least two operations of treating one or more building materials with the carbon dioxide in such a manner as to permanently sequester the carbon dioxide; treating a process water produced in the building materials facility with the carbon dioxide to lower a pH of the process water, or treating concrete or a concrete component at the building materials production facility to cool the concrete or component are performed.
 4. The method of claim 1 wherein all three of treating one or more building materials with the carbon dioxide in such a manner as to permanently sequester the carbon dioxide; treating a process water produced in the building materials facility with the carbon dioxide to lower a pH of the process water, or treating concrete or a concrete component at the building materials production facility to cool the concrete or component are performed.
 5. A method of sequestering carbon dioxide from cement and lime production facilities comprising i) treating flue gas comprising carbon dioxide from the cement or lime manufacturing process to render the carbon dioxide transportable, wherein the amount of flue gas treated is 1-8% of the total flue gas produced at the cement and/or lime production facility; ii) transporting the carbon dioxide to a precast concrete production facility; and iii) treating a precast object comprising a cement binder with the carbon dioxide, wherein the treatment with carbon dioxide occurs upstream of a curing operation.
 6. The method of claim 1 wherein the flue gas comprises preheater exhaust gas.
 7. The method of claim 6 wherein the preheater exhaust gas is preheater exhaust gas at a discharge of an exhaust fan.
 8. The method of claim 7 wherein the treating the flue gas from the preheater discharge comprises treating the flue gas to render the carbon dioxide transportable in liquid form.
 9. The method of claim 8 wherein the operation of treating one or more building materials with the carbon dioxide in such a manner as to permanently sequester the carbon dioxide in the building material is performed.
 10. The method of claim 1 comprising performing the operation of treating one or more building materials with the carbon dioxide in such a manner as to permanently sequester the carbon dioxide in the building material wherein the building material comprises a cement binder.
 11. The method of claim 1 comprising performing the operation of treating one or more building materials with the carbon dioxide in such a manner as to permanently sequester the carbon dioxide in the building material wherein treating a precast object comprising a cement binder with the carbon dioxide, wherein the carbon dioxide is contacted with the building material at a pressure of 0-25 psi.
 12. The method of claim 1 wherein the flue gas used in the method is 1-10% of the total flue gas produced at the cement and/or lime production facility.
 13. The method of claim 1 wherein the flue gas further comprises one or more impurities that normally would be removed before the flue gas is vented to the atmosphere but that in the method of claim 1 remains present in the carbon dioxide separated from the flue gas, and is used in performing the at least one operation of part (iii).
 14. The method of claim 13 wherein the at least one impurity comprises NOx, SOx, HCl, dust, metals, CO, or volatile organic compounds, or a combination thereof.
 15. The method of claim 13 wherein the operation of part (iii) comprises treating one or more building materials with the carbon dioxide in such a manner as to permanently sequester the carbon dioxide in the building material, and wherein the one or more impurities is also sequestered in the building material.
 16. The method of claim 1 further comprising using waste heat from the cement and/or lime production process in the extraction of carbon dioxide from the flue gas.
 17. The method of claim 3 wherein the at least two operations comprise treating one or more building materials with the carbon dioxide in such a manner as to permanently sequester the carbon dioxide; and treating a process water produced in the building materials facility with the carbon dioxide to lower a pH of the process water.
 18. The method of claim 17 wherein the treating of one or more building materials with the carbon dioxide in such a manner as to permanently sequester the carbon dioxide comprises using process water that has been treated with carbon dioxide to lower a pH of the process water as mix water in a wet cement mix that is used to produce the one or more building materials.
 19. The method of claim 1 wherein at least a portion of the transportable carbon dioxide produced in step (i) is produced in liquid form.
 20. The method of claim 1 wherein the transportable carbon dioxide produced in step 1 has a carbon dioxide content of greater than 60%.
 21. The method of claim 1 wherein treating the flue gas in step (i) comprises cryogenic separation of carbon dioxide from the flue gas.
 22. The method of claim 1 wherein the cement and/or lime production facility at which the carbon dioxide is rendered transportable is no more than 100 miles from the building materials production facility at which the at least one operation of step (iii) is performed.
 23. The method of claim 1 wherein the amount of flue gas treated is 1-50% of the total flue gas produced at the cement and/or lime production facility.
 24. The method of claim 1 wherein the amount of flue gas treated is 1-30% of the total flue gas produced at the cement and/or lime production facility. 